1. Field of the Invention
Aspects of the present invention relate to an organic thin film transistor, and a flat display device having the organic thin film transistor, and more particularly, to an organic thin film transistor in which a source electrode and a drain electrode are formed in a double layer structure to aid the patterning of an organic semiconductor layer using a laser beam, and a flat display device having the same.
2. Description of the Related Art
Thin film transistors (TFTs) are used in flat display devices, such as, for example, liquid crystal display (LCD) devices, organic light emitting display (OLED) devices, and inorganic light emitting display devices. The TFTs are used as switching devices to control an operation of each pixel and as driving devices to drive each pixel.
Typical TFTs include source/drain regions doped with a high concentration of a dopant and an organic semiconductor layer having a channel region formed between the source and drain regions, a gate electrode located on a region corresponding to the channel region and insulated from the semiconductor layer, and source and drain electrodes which respectively contact the source/drain regions.
TFTs are in demand not only for display devices but also in various other fields, such as smart cards, E-paper, roll-up displays, etc. A common aspect required by these thin electronic devices is flexibility. For this reason, the substrate that forms the TFTs must have flexibility, like a plastic substrate.
During manufacturing of organic TFTs, source and drain electrodes are formed of a noble metal such as Au, Pt, or Pd to make good electrical contact with an organic semiconductor layer. However, when the source and drain electrodes are formed of a noble metal, the absorption rate of a 248 nm UV laser beam is increased. Accordingly, when the organic semiconductor layer is patterned on an organic TFT using the laser beam, cracks are generated in the source and drain electrodes, as shown in FIG. 1.